All‐polymer solar cells (all‐PSCs) have drawn tremendous research interest in recent years, due to their inherent advantages of good film formation, stable morphology, and mechanical flexibility. The ...most representative and most widely used n‐CP acceptor was the naphthalene diimide based D‐A copolymer N2200 before 2017, and the power conversion efficiency (PCE) of the all‐PSCs based on N2200 reached over 8% in 2016. However, the low absorption coefficient of N2200 in the near‐infrared (NIR) region limits the further increase of its PCE. In 2017, we proposed a strategy of polymerizing small‐molecule acceptors (SMAs) to construct new‐generation polymer acceptors. The polymerized SMAs (PSMAs) possess low band gap and strong absorption in the NIR region, which attracted great attention and drove the PCE of the all‐PSCs to over 15% recently. In this Minireview we explain the design strategies of the molecular structure of PSMAs and describe recent research progress. Finally, current challenges and future prospects of the PSMAs are analyzed and discussed.
This Minireview describes developments in all‐polymer solar cells containing a new type of n‐type conjugated polymer, polymerized small‐molecule acceptors (PSMAs). PSMAs combine the merits of small‐molecule acceptors (narrow band gap, strong absorption, and suitable electronic energy levels) with the good film formation, higher morphology and light‐irradiation stability of polymers.
Efficient emission of purely organic room‐temperature phosphorescence (RTP) is of great significant for potential application in optoelectronics and photobiology. Herein, we report an uncommon ...phosphorescent effect of organic single molecule enhanced by resulting supramolecular assembly of host–guest complexation. The chromophore bromophenyl‐methyl‐pyridinium (PY) with different counterions as guests display various phosphorescence quantum yields from 0.4 % to 24.1 %. Single crystal X‐ray diffraction results indicate that the chromophore with iodide counterion (PYI) exhibits the highest efficiency maybe due to the halogen‐bond interactions. Significantly, the nanosupramolecular assembly of PY chloride complexation with the cucurbit6uril gives a greatly enhanced phosphorescent quantum yield up to 81.2 % in ambient. Such great enhancement is because of the strict encapsulation of cucurbit6uril, which prevents the nonradiative relaxation and promotes intersystem crossing (ISC). This supramolecular assembly concept with counterions effect provides a novel approach for the improvement of RTP.
An uncommon phosphorescent effect of an organic single molecule enhanced by supramolecular assembly of host–guest complexation is reported. The chromophore bromophenyl‐methyl‐pyridinium (PY) gives an enhanced phosphorescent efficiency of 81.2 % under ambient conditions after complexation with cucurbit6uril. The strict encapsulation of cucurbit6uril suppresses the nonradiative relaxation and promotes intersystem crossing.
Precisely interpreting frequency response analysis (FRA) curves is crucial when investigating mechanical malfunctions in power transformer windings (TWs). However, many conventional explanations of ...FRA features cannot be validated by an equivalent circuit (EC) that represents winding structures using resistance, inductance, and capacitance components in a ladder network. Incorrect interpretation can lead to misdiagnosis and confusion in asset management. Previous ECs are often proposed by analysing winding structures without rigorous verification compared to the corresponding FRA data. The specific EC is acquired using the transfer function (TF) derived from the measured FRA data. This allows for the establishment of the relationship between TW FRA curves, TF equations, and EC topologies. The precise interpretation of FRA curves can be achieved by closely observing the FRA curves created from TFs and ECs. The remarkable similarity between the measured and modelled FRA curves verifies the authenticity of the derived ECs. This significant achievement clarifies many misunderstandings regarding FRA and represents a substantial advancement in FRA technology.
The ground‐breaking achievement of this study lies in the derivation of authentic equivalent circuit models based on the obtained transfer function equation through the processing of power transformer FRA data. These equivalent circuit models can accurately characterise the features exhibited in FRA curves.
The photoluminescence of carbon nanodots (C‐dots) can be tuned by changing their surface chemistry or size because the photoluminescence is a function of the surface‐state electronic transitions. ...Increasing the degree of surface oxidation leads to a narrowing of the energy gap of the surface; meanwhile, larger C‐dots with an extensive π‐electron system, which can couple with surface electronic states, can also lead to a narrowing of the energy gap of the surface states.
This study characterizes the demographic, epidemiologic, and clinical characteristics of hospitalized infants diagnosed with coronavirus disease 2019 infection between December 8, 2019, and February ...6, 2020, in China.
Improving the stability of lead halide perovskite quantum dots (QDs) in a system containing water is the key for their practical application in artificial photosynthesis. Herein, we encapsulate ...low‐cost CH3NH3PbI3 (MAPbI3) perovskite QDs in the pores of earth‐abundant Fe‐porphyrin based metal organic framework (MOF) PCN‐221(Fex) by a sequential deposition route, to construct a series of composite photocatalysts of MAPbI3@PCN‐221(Fex) (x=0–1). Protected by the MOF the composite photocatalysts exhibit much improved stability in reaction systems containing water. The close contact of QDs to the Fe catalytic site in the MOF, allows the photogenerated electrons in the QDs to transfer rapidly the Fe catalytic sites to enhance the photocatalytic activity for CO2 reduction. Using water as an electron source, MAPbI3@PCN‐221(Fe0.2) exhibits a record‐high total yield of 1559 μmol g−1 for photocatalytic CO2 reduction to CO (34 %) and CH4 (66 %), 38 times higher than that of PCN‐221(Fe0.2) in the absence of perovskite QDs.
Pores and dots: CH3NH3PbI3 (MAPbI3) perovskite quantum dots were encapsulated in the pores of iron‐porphyrin derived metal–organic frameworks (MOFs) of PCN‐221(Fex) to give an efficient photocatalytic system, which has significantly enhanced catalytic efficiency and stability for visible‐light‐driven CO2 reduction using water as an electron source.
Solving power flow (PF) equations is the basis of power flow analysis, which is important in determining the best operation of existing systems, performing security analysis, etc. However, PF ...equations can be out-of-date or even unavailable due to system dynamics, and uncertainties, making traditional numerical approaches infeasible. To address these concerns, researchers have proposed data-driven approaches to solve the PF problem by learning the mapping rules from historical system operation data. Nevertheless, prior data-driven approaches suffer from poor performance, and generalizability, due to overly simplified assumptions of the PF problem or ignorance of physical laws governing power systems. In this paper, we propose a physics-guided neural network to solve the PF problem, with an auxiliary task to rebuild the PF model. By encoding different granularity of Kirchhoff's laws, and system topology into the rebuilt PF model, our neural-network based PF solver is regularized by the auxiliary task, and constrained by the physical laws. The simulation results show that our physics-guided neural network methods achieve better performance, and generalizability compared to existing unconstrained data-driven approaches. Furthermore, we demonstrate that the weight matrices of the proposed neural networks embody power system physics by showing their similarities with the bus admittance matrices.
The size of C‐nanodots can be electrochemically tuned by changing the applied potential during their preparation. The higher the applied potential, the smaller the resulting C‐nanodots. Moreover, the ...surface oxidation degree of the C‐nanodots can also be electrochemically tuned. The red‐shift of emission independent of the size provides an insight into the luminescence mechanism of C‐nanodots.
Addressing the challenges faced by team leaders in fostering both individual and team creativity, this research developed and tested a multilevel model connecting dual-focused transformational ...leadership (TFL) and creativity and incorporating intervening mechanisms at the two levels. Using multilevel, multisource survey data from individual members, team leaders, and direct supervisors in high-technology firms, we found that individual-focused TFL had a positive indirect effect on individual creativity via individual skill development, whereas team-focused TFL impacted team creativity partially through its influence on team knowledge sharing. We also found that knowledge sharing constituted a cross-level contextual factor that moderated the relationship among individual-focused TFL, skill development, and individual creativity. We discuss the theoretical and practical implications of this research and offer suggestions for future research.
It is very important to fine‐tune the nanoscale morphology of donor:acceptor blend active layers for improving the photovoltaic performance of all‐small‐molecule organic solar cells (SM‐OSCs). In ...this work, two new small molecule donor materials are synthesized with different substituents on their thiophene conjugated side chains, including SM1‐S with alkylthio and SM1‐F with fluorine and alkyl substituents, and the previously reported donor molecule SM1 with an alkyl substituent, for investigating the effect of different conjugated side chains on the molecular aggregation and the photophysical, and photovoltaic properties of the donor molecules. As a result, an SM1‐F‐based SM‐OSC with Y6 as the acceptor, and with thermal annealing (TA) at 120 °C for 10 min, demonstrates the highest power conversion efficiency value of 14.07%, which is one of the best values for SM‐OSCs reported so far. Besides, these results also reveal that different side chains of the small molecules can distinctly influence the crystallinity characteristics and aggregation features, and TA treatment can effectively fine‐tune the phase separation to form suitable donor–acceptor interpenetrating networks, which is beneficial for exciton dissociation and charge transportation, leading to highly efficient photovoltaic performance.
The active layer morphology of all‐small‐molecule organic solar cells (SM‐OSCs) is tuned by side chain engineering of the donor molecules and thermal annealing (TA) of the devices. An SM‐OSC based on A–D–A‐structured SM1‐F with fluorine and alkyl substituents as the donor and Y6 as the acceptor, and with TA, demonstrates a high power conversion efficiency of 14.07%.
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